The purpose of this project is to determine the transport and permeability properties of the epithelia of the cornea and of the blood-ocular barriers. The ultimate aims are: 1) an understanding of corneal hydration and transparency in physiological and diseased conditions; 2) to determine the permeability and transport characteristics of the blood-retina barrier in normal animals and in animal models of retinal degeneration. The methods to be employed consist of the use of ion-sensitive microelectrodes and analytical methods such as atomic absortion spectrophotometry, chloridometry, etc. to detect ionic gradients; detection of radioisotopic fluxes across the epithelia in vivo, by equilibration of molecules in blood and detection in ocular fluids, and compartment analysis by use of the tissues as membranes and determination of their electrical potential, short-circuit current, molecular fluxes and water movements with specific electronic equipment including an automatic volumetric water flow unit. Ca effect and distribution in corneas and isolated retina pigment epithelium will be studied by means of compartmental analysis of tissue strips in vitro, as well as the effects of changes in membrane fluidity.